Measurement of atoms, fragments of molecules, molecules, droplets and particles (simply denoted particles hereafter) by measurement of a single time-of-flight (TOF) value is a convenient method utilized in TOF mass spectroscopy analysis of atomic and molecular species and in the characterization of particles suspended in a gas by various particle TOF spectrometer devices. See, for example, U.S. Pat. No. 4,917,494. There is a problem with such devices in that only a single TOF value is measured and utilized to provide information about the character of the particle. When a TOF value depends on two or more particle properties, the TOF provides a single property of the particle when all other particle properties that influence the TOF are known. When two or more such properties are not known, a single measured TOF cannot generally be used to accurately determine another particle property besides the TOF without substantial uncertainty. For example, size can be precisely determined in an aerodynamic device when values of TOF and other particle properties, such as mass density and shape, are known. Likewise, a mass species is distinguished from another mass species having the same charge to mass ratio or associated with the same mass species having a different charge to mass ratio by use of a TOF value obtained from a TOF mass spectrometer device only when at least one other property value of the particle is known.
Because of the limited information provided by currently used single TOF methods and devices for characterizing particles, improved methods are desired.
It is an object of this invention to provide an improved method for characterizing particles by determining various property values.
It is another object of this invention to provide an aerodynamic method for characterizing particles.
It is a further object of this invention to provide a rapid method for determining at least two property values for one or more particles.
It is still another object of this invention to detect the passage of at least one particle at each of at least three detection locations while the particle is acted on by forces dependent on the property values of the particle(s) and to use the time differences between the passages of the particle(s) past the detection locations to determine at least two property values of the particle(s).
It is still yet another object of this invention to process signals from the detector(s) so as to obtain the correct set of TOF values for each particle which passes through the set of detection locations.
It is still another object of this invention to provide a method for determination of a size, mass, shape factor or electric charge property value of a particle.
It is still a further object of this invention to provide a method for determination of the amount of material dissolved and/or suspended in a gas or liquid by determination of the mass, mass fraction, mass concentration, volume, volume fraction or volume concentration of the dissolved or suspended material in the gas or liquid.